reinforced concrete wide beam

[Groszni]

hello engtips users
i wanna ask what are the considerations of using a wide beam?
ive seen so many carpark using this kind of beam.
what are some provision to design it?
regards.

 

[Ingenuity]

Do you refer to band beams and slabs, like this?

If so, this reference may be of assistance: Link

Extract:

 

[Groszni]

@ingenuity yes! thank you so much, do you know why would we should use some kind of beam that lack of moment of inertia like that? do you have more references that you could email me maybe?

 

[molibden]

I think it's obvious why - you have it written as Advantages.

I would design it as a normal beam.

 

[Groszni]

@molibden yeah thank you i didnt see the advantages and the disadvantages earlier, do you have any guide on how to design a ramp?

 

[Trenno]

You're designing a carparking structure with band beams, that is also ramped?

Perhaps assume they are flat as a first pass, but accounting the true span as opposed to the plan length. You'll also end up with a horizontal thrust that will need to be collected by your lateral system.

 

[Groszni]

@trenno no im not, its a multistory car park, it needs the ramp to move to another level right?

 

[KootK]

One important design feature with band beans is shear at the supports. With your beams wider than your columns, a conventional one way shear check on the whole cross section is inadequate. You get a shear situation that more resembles punching shear.

This is a very popular system in my area for below grade parking structures. I may disagree with with one of the disadvantages listed above. Wide beams accommodate vertical penetrations relatively easily and I consider that a benefit of the system.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[Groszni]

@kootk thank you! do you know some provision that regulate such thing like the dimension and stuff?

 

[KootK]

Depends where you're at. Canada has a few provisions related to the detailing of the system but designers are at liberty to select their own proportions. Typical systems around here look like this:

- minimum drive isle width.
- columns at three stall spacings max.
- 7" slab
- 16" x 48" wide beams.

There is so much local experience with this that we don't usually even bother to check deflections.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.